Facebook Inc. suffered the biggest-ever one-day loss in market value for a U.S.-listed company, a punishing reversal for a company that has led a yearslong tech-stock surge.

Facebook shares fell 19% to $176.26, erasing about $119.1 billion in market value, after the Menlo Park, Calif., company warned late Wednesday about slowing growth. Facebook’s loss in market value Thursday is larger than 457 of the 500 companies in the S&P 500 and bigger than the aggregate valuation of the bottom 20 companies in the S&P 500.